The interreaction of amilorine and lithium will be studied to determine if their effects are additive. This part of the study seeks both to determine if amiloride can block the effect of lithium on acidification, as previously has been shown to be true as regards the effect of lithium on urinary concentration, as well as to examine the possibility that there may be more than one pathway for hydrogen ion secretion. We will examine the effect of amphotericin on urinary acidification. If a clearcut acidification defect is demonstrated, we will attempt to determine if the defect is of the secretory or gradient type. We plan to examine in detail the acidification defect, recently described by us, induced by glucose and insulin administration. In addition to determining the type of acidification defect present we will also determine if glucose and insulin administration inhibits urinary concentrating ability as is the case in the other experimental defects examined by us.